Have you seen this one before? Do you know a workaround? (DMD  v2.063.2, on OX X 10.9)

file.d:

    extern(C)
    {
        int x = 0;
        void setx();
        void printx();
    }

    void main()
    {
        setx(); // sets x = 42
        writeln(x); // prints x = 0
        printx(); // prints x = 42
        x = 7;
        printx(); // prints x = 42
    }



file.c:

    #include <stdio.h>

    extern int x;

    void setx()
    {
        x = 42;
    }

    void printx()
    {
        printf("%d\n", x);
    }

Output:

    0
    42
    42

On Wednesday, 25 September 2013 at 04:13:02 UTC, Luís Marques wrote:
> Have you seen this one before? Do you know a workaround? (DMD  v2.063.2, on OX X 10.9)
>
> file.d:
>
>     extern(C)
>     {
>         int x = 0;
>         void setx();
>         void printx();
>     }
>
>     void main()
>     {
>         setx(); // sets x = 42
>         writeln(x); // prints x = 0
>         printx(); // prints x = 42
>         x = 7;
>         printx(); // prints x = 42
>     }
>
>
>
> file.c:
>
>     #include <stdio.h>
>
>     extern int x;
>
>     void setx()
>     {
>         x = 42;
>     }
>
>     void printx()
>     {
>         printf("%d\n", x);
>     }
>
> Output:
>
>     0
>     42
>     42

don't you need extern __gshared on the var?

extern __gshared int x;

On Wednesday, 25 September 2013 at 04:35:35 UTC, growler wrote:
> On Wednesday, 25 September 2013 at 04:13:02 UTC, Luís Marques wrote:
>> Have you seen this one before? Do you know a workaround? (DMD  v2.063.2, on OX X 10.9)
>>
>> file.d:
>>
>>    extern(C)
>>    {
>>        int x = 0;
>>        void setx();
>>        void printx();
>>    }
>>
>>    void main()
>>    {
>>        setx(); // sets x = 42
>>        writeln(x); // prints x = 0
>>        printx(); // prints x = 42
>>        x = 7;
>>        printx(); // prints x = 42
>>    }
>>
>>
>>
>> file.c:
>>
>>    #include <stdio.h>
>>
>>    extern int x;
>>
>>    void setx()
>>    {
>>        x = 42;
>>    }
>>
>>    void printx()
>>    {
>>        printf("%d\n", x);
>>    }
>>
>> Output:
>>
>>    0
>>    42
>>    42
>
> don't you need extern __gshared on the var?
>
> extern __gshared int x;

http://dlang.org/interfaceToC.html (see last section at bottom of
page)

On 9/24/2013 9:13 PM, "Luís Marques" <luis@luismarques.eu>" wrote:
> Have you seen this one before? Do you know a workaround? (DMD v2.063.2, on OX X
> 10.9)
>
> file.d:
>
>      extern(C)
>      {
>          int x = 0;

This x is put in thread local storage.

>          void setx();
>          void printx();
>      }
>
>      void main()
>      {
>          setx(); // sets x = 42
>          writeln(x); // prints x = 0
>          printx(); // prints x = 42
>          x = 7;
>          printx(); // prints x = 42
>      }
>
>
>
> file.c:
>
>      #include <stdio.h>
>
>      extern int x;

This x is put in thread global storage.

>
>      void setx()
>      {
>          x = 42;
>      }
>
>      void printx()
>      {
>          printf("%d\n", x);
>      }
>
> Output:
>
>      0
>      42
>      42

So you've got two different x's here.

Declare the first one as:

    __gshared int x = 0;

Oops :-)

I just assumed too quickly that it was another consequence of the DMD / (GCC, Clang) section mismatch I reported some days ago (http://forum.dlang.org/thread/gqxtzdbhnzkslnltqrmo@forum.dlang.org), I didn't even think it was a basic PEBCAK.

My bad --;;

I guess I also implicitly assumed extern(C) implied __gshared... ("make it the same as C, not just the mangling"). And TLS is so implicit in D2 that one can even forget about it :-)

On 2013-09-25 06:49, "Luís Marques" <luis@luismarques.eu>" wrote:

> I guess I also implicitly assumed extern(C) implied __gshared... ("make
> it the same as C, not just the mangling"). And TLS is so implicit in D2
> that one can even forget about it :-)

Well, C has thread local, via the extension "__thread" or via C++ "thread_local". So if extern (C) implied "__gshared", how would one declare an extern (C) thread local variable?

-- 
/Jacob Carlborg

On 25 September 2013 10:40, Jacob Carlborg <doob@me.com> wrote:
> On 2013-09-25 06:49, "Luís Marques" <luis@luismarques.eu>" wrote:
>
>> I guess I also implicitly assumed extern(C) implied __gshared... ("make
>> it the same as C, not just the mangling"). And TLS is so implicit in D2
>> that one can even forget about it :-)
>
>
> Well, C has thread local, via the extension "__thread" or via C++
> "thread_local". So if extern (C) implied "__gshared", how would one declare
> an extern (C) thread local variable?
>
> --
> /Jacob Carlborg

Especially considering that __thread is deprecated/error in D now. ;)

-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';